This invention relates to a polishing and cleaning compound device which polishes and cleans both surfaces of a thin disc-shaped work piece in series such as a substrate for magnetic discs, a wafer, a glass substrate for a liquid-crystal display and a glass substrate for photomask.
JP 2002-254301 A discloses a polishing device which holds careers having a plurality of holes for holding a plurality of work pieces between upper and lower press pratens and makes them revolve and rotate on its own axis in normal and inverse directions alternatively to polish both sides of a plurality of work pieces.
JP 2001-144057 A discloses that, for example, a process for polishing surfaces of wafers is constituted of a plurality of polishing processes such as a rough polishing process, a precise polishing process, and a finish process, whose problem is to well remove slurry which is clung on wafers when the wafers are moved between the polishing stations. Accordingly, the patent reference discloses that the wafers are washed in a condition held on holding heads and washed in a condition installed on a holding base, and further, that the holding heads are washed independently.
Currently, there is a demand to polish a large number of thin disc-shaped work pieces such as wafers, and up to now, as disclosed in JP 2002-254301 A, a plurality of work pieces are polished once by making a plurality of careers each of which can receive a plurality of work pieces and revolve and rotate on its axis between the upper and the lower press pratens which have polishing surfaces rotating on their axes and on which slurry is supplied. In this case, when the work pieces are taken out after polishing, polished surfaces of the work pieces are changed by the slurry clung thereon, so that a disadvantage arises in that the work pieces must be taken out as soon as possible and qualities of the work pieces are changed according to an order in which the work pieces are taken out.
In addition, as disclosed in JP 2001-144057 A, it is preferable that removal of the slurry is carried out every polishing process, but as a result, a disadvantage arises in that the process is complicated. Furthermore, a disadvantage arises in that abrasive cloth is hardened because of a time interval between the polishing process and the cleaning process, such that a problem of a decrease in a quality of polishing arises.